So I've been looking at my car the last couple months and the oem heat shielding/sound deadener on the hood and firewall has really been annoying me. Now granted this is definitely not required, but perfection is in the details for me. So here is my question, what is the purpose of these. The aluminized outer layer on the hood underneath the "insulator" screen says heat shield, but my theory is wouldn't you want as much heat evacuated out of the engine bay, while keeping the large majority in the exhaust piping to keep up the velocity. If this was true wouldn't you want the hood and firewall bare so they act as a heatsink to collect the ambient heat and then quickly disperse it through the airflow. If not please do correct me as there is much better heat management materials than the oem stuff, but if all it is is a sound deadner then I can deal with a louder car in the favor of a more efficient system.

 

Think thru your outline---you are correct-- according to my egt gauge my cars exhaust temp is over 1000f now apply that heat to a painted surface and what happens to your hood? Granted there are many other factors --but thats why there is a heat shield and at idle/ in traffic, there is no air flow.

 

That brings up a good point I hadn't thought through, under normal driving conditions sitting and idling the hood will soak a good amount of heat which won't be dissipated quickly at say 40 deg F but I have the unique opportunity of living in Alaska. This creates a situation where 9 months out of the year is winter. While it has been unusually warm this winter it generally means that 3 months straight during this period we see -40f and anywhere from 20 to -20f the other 6 months, so I guess under ideal conditions such as these would it be more ideal to leave those portions bare. Basically I have covered all other surfaces other than the radiator and intercooler with reflect-a-gold to keep the heat out (as I see that those surfaces would benefit more from air flowing over them more than keeping temps out as heat management coatings both keep heat out and cold out). Of course this is a completely mature conversation in which I am looking for people to scientifically give me a reason for why I am wrong (I prefer you are wrong because of xyz based on these tests vs I have x amount of years doing things one way and you are just stupid cuz I say so). I have a feeling there is a good reason why Mitsubishi put the heatshield there, just if they did for reasons other than sound deadening there are other more modern materials that are more effective, on the other hand if the main reason is sound deadening than I would rather strip those parts out for peak performance but would prefer to keep the vent piece in as it prevents snow from building up in my engine bay. I know really long and kinda confusing as to what I'm getting at as I'm a little scatter brained, and sorry for that. Also in the above example yes the hood soaks up a good amount of heat in a small area over the exhaust manifold area but if this area in my mind wouldn't that allow the heat to be spread over a larger surface area if the hood was bare, in turn allowing it to dissipate more quickly, again I am probably wrong but just looking for a reason why I am.